I SPOTTED the word quinquagenarian yesterday and decided to use it while I still can.

Sadly, it took a while to type. This wasn’t only because it’s an alphabetical mouthful. A Mexican woman who used to be a ballerina should take some of the blame. She came down for breakfast just as the word had been typed and after that I became distracted. Among the oddities of my life nowadays, sharing the Airbnb breakfast table with charming a Mexican woman can count as a bonus.

It was less of a bonus last night when she went out at 5pm and didn’t return until 2.30am. This is not a problem to any degree but it is the sort of thing that triggers my insomnia.

After falling asleep easily, I woke up a couple of hours later, and that was that. In the restless hours I began to wonder if she’d returned, and if not what might have happened. The reading light went on and off; I went downstairs to see if the sofa would be more conducive to sleep. It wasn’t so I went upstairs again. At around four, long after I’d heard our guest return, and after our daughter had returned too, I eventually fell asleep, back on the sofa  after failing to find the trick of it upstairs.

So this morning I went out for a sleepy-headed run. Which is where quinquagenarian comes into the equation. You see I spotted the word yesterday in the Guardian Weekend supplement, as used by a letter writer who was reacting to the previous week’s What I’m Really Thinking item, in which a pensioner had said he was mocked for jogging. “I’m a quinquagenarian and hope I never have to hang up my running shoes,” the letter writer said.

I have been mocked for jogging, too. Years ago now, when my legs were stronger and my head not quite so bald, two tracky-bottomed yobs took the piss out of me as I ran towards them. “You’re too old for that,” one of them said. I seem to recall that he was overweight and eating a sausage role. And if he wasn’t, he is now and it serves him right. I ran on and left him to his baggy stomach and his bakery product.

Like that letter writer, I hope not to have to hang up my running shoes for a while yet. Or my squash racket: one of my opponents is a couple of years younger than me, the other five years older.

I looked up quinquagenarian to discover that it means someone in their fifties. So I thought I’d better use the word before I stumble over my laces and end up as a sexagenarian. And I know that the Latin language is to blame, but is it some sort of a joke to label people in their sixties with a word that begins with “sex”?

The Mexican woman has just come down again having failed to find our downstairs shower – “Did you say there was a shower somewhere else in the house?”

I direct her to the shower and then return to the laptop. It turns out that she met some people in a bar, then met more people in a different bar, and had lovely night out in York, catching a taxi back in the early hours. And she is 32 and only here for the night and my responsibility doesn’t extend beyond a pleasant breakfast chat. Still the funniest things can disrupt the sleep of a quinquagenarian.